The efficiency of transport into the stratosphere via the Asian and North American summer monsoon circulations
The efficiency of transport into the stratosphere via the Asian and North American summer monsoon circulations
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DOI：
10.5194/acp-19-15629-2019
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发表时间：
2019-12
影响因子：
6.3
通讯作者：
Xiaolu Yan;P. Konopka;F. Ploeger;A. Podglajen;Jonathon S. Wright;R. Müller;M. Riese
中科院分区：
文献类型：
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作者：
Xiaolu Yan;P. Konopka;F. Ploeger;A. Podglajen;Jonathon S. Wright;R. Müller;M. Riese
抽象的。污染物通过亚洲夏季风（ASM）或北美夏季风（NASM）进入平流层可能会影响当地和全球的大气组成和气候。我们确定和研究的强大的传输特性，从ASM和NASM地区的平流层使用拉格朗日化学传输模型CLaMS驱动的ERA-Interim和MERRA-2再分析。特别是，我们量化的相对影响的ASM和NASM平流层的组成和调查的运输途径和效率的空气质量的运输起源于不同的高度在这两个季风区的平流层。2010-2013年7月和8月，我们在ASM和NASM源区从对流层中层到平流层下层的几个垂直层中释放人工示踪剂，并跟踪它们的演变，直到第二年夏天。我们发现，更多的空气质量从ASM和NASM地区输送到热带平流层，甚至南半球平流层，当示踪剂释放明显低于对流层顶（350-360 K）比当他们被释放接近对流层顶（370-380 K）。对于在对流层顶附近（370-380 K）释放的示踪剂，输送主要进入北方半球平流层下部。不同垂直层的空气来源的结果揭示了两个传输路径从上层对流层在ASM和NASM地区的热带管道：㈠准水平输送到对流层顶以下的热带，然后通过热带上升流上升到平流层，及（ii）上升至亚洲运动/北美运动内的平流层，然后进行准-水平输送到热带低平流层，并进一步输送到热带管道。总体而言，热带路径（i）比季风路径（ii）快，特别是在上升分支。起源于ASM对流层上部（350-360 K）的热带管道中的空气丰度与源示踪剂释放后10个月（次年初夏）从热带直接上升到热带管道的空气丰度相当。ASM对热带管道的空气质量贡献比NASM的相应贡献大约3倍。在370-380 K时，ASM区域进入热带管道的输送效率最大，即目的区域内的空气质量分数由起源区域的质量归一化。虽然NASM对平流层的贡献小于ASM或热带，但NASM的输送效率与热带相当。
Abstract. Transport of pollutants into the stratosphere via the Asian summer monsoon (ASM) or North American summer monsoon (NASM) may affect the atmospheric composition and climate both locally and globally. We identify and study the robust characteristics of transport from the ASM and NASM regions to the stratosphere using the Lagrangian chemistry transport model CLaMS driven by both the ERA-Interim and MERRA-2 reanalyses. In particular, we quantify the relative influences of the ASM and NASM on stratospheric composition and investigate the transport pathways and efficiencies of transport of air masses originating at different altitudes in these two monsoon regions to the stratosphere. We release artificial tracers in several vertical layers from the middle troposphere to the lower stratosphere in both ASM and NASM source regions during July and August 2010–2013 and track their evolution until the following summer. We find that more air mass is transported from the ASM and NASM regions to the tropical stratosphere, and even to the southern hemispheric stratosphere, when the tracers are released clearly below the tropopause (350–360 K) than when they are released close to the tropopause (370–380 K). For tracers released close to the tropopause (370–380 K), transport is primarily into the northern hemispheric lower stratosphere. Results for different vertical layers of air origin reveal two transport pathways from the upper troposphere over the ASM and NASM regions to the tropical pipe: (i) quasi-horizontal transport to the tropics below the tropopause followed by ascent to the stratosphere via tropical upwelling, and (ii) ascent into the stratosphere inside the ASM/NASM followed by quasi-horizontal transport to the tropical lower stratosphere and further to the tropical pipe. Overall, the tropical pathway (i) is faster than the monsoon pathway (ii), particularly in the ascending branch. The abundance of air in the tropical pipe that originates in the ASM upper troposphere (350–360 K) is comparable to the abundance of air ascending directly from the tropics to the tropical pipe 10 months after (the following early summer) the release of the source tracers. The air mass contributions from the ASM to the tropical pipe are about 3 times larger than the corresponding contributions from the NASM. The transport efficiency into the tropical pipe, the air mass fraction inside this destination region normalized by the mass of the domain of origin, is greatest from the ASM region at 370–380 K. Although the contribution from the NASM to the stratosphere is less than that from either the ASM or the tropics, the transport efficiency from the NASM is comparable to that from the tropics.